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reconstruction. However, its poor malleability, donor site replaced by titanium.
morbidity and fluctuant resorption rates may be problematic
[Figure 1]. The unpredictable resorption rates of autologous Titanium mesh has been approved by the Food and Drug
bone especially iliaca can even reach 80%, which increase Administration since 1984, and now is accepted throughout
[13]
the risk of complications. Resorption may be decreased by the would to be used in the craniomaxillofacial surgery,
fixating of the graft, which promotes revascularization and especially in large defects. Titanium is chemically similar
osteoconduction. [15] to calcium which makes it physiologically inert, and tissue
tolerant. Titanium has a high corrosion resistance due to
Another option is cartilage graft, which compared to the the spontaneously forming thin oxide layers on the surface.
“gold standard” bone graft is easier to harvest, is more This guarantees that the material behaves passively in order
malleable, and has less resorption. The nasal septum, not to provoke toxic nor allergic reactions [Figure 2].
[27]
[16]
conchal cartilage and costal cartilage are the common Computer-assisted designed and manufactured titanium
donor sites. The nasal septum is advantageous owing to the implants have enabled optimal reconstructive surgery, with
rapid harvest time and the minimal cosmetic and functional the protection of vital structures such as the optic nerve.
[28]
morbidity. [17,18] Bayat et al. performed a randomized However, it is costly and may have irregular edges that
[19]
clinical trial and found a superior effect for nasal cartilage may impinge on soft tissue. Furthermore, fibrous tissue
compared to conchal cartilage with respect to the incidence will incorporate the mesh-holes, which can make implant
of enophthalmos at the 3-6 months follow-up point. replacement technically difficult. [29]
Whereas, the autologous cartilage still cannot avoid donor
site morbidity and is limited in quantity. POLYMERS

Allograft is transplanted tissue from human cadaver. Polymers are large molecules comprising of multiple repeated
Lyophilized dura mater, demineralized human bone, subunits, and can be categorized into absorbable and non-
lyophilized cartilage, irradiated fascia lata are types of absorbable (permanent), or porous and non-porous types.
harvested tissues. The advantages of allograft include a
decreased surgical time, preoperative customizability, Since 1990s, porous ultra-high-density polyethylene (PE,
absence of donor site morbidity (only in cadavers), and medpor) sheets have been widely used in smaller orbital
abundant availability. Lyophilized dura (Lyodura) was once floor defects [Figure 3]. It’s non-absorbable and easily
the standard for the repair of smaller orbital defects. malleable into shapes. The smooth surface of medpor allows
[20]
However, it became controversial after a report of tissues within the orbit to move around freely. Connective
[26]
Creutzfeldt-Jakob prion disease in a patient who received tissue and vascular components can grow into the pores
dura. The disadvantages of allograft include a resorption which provides great biocompatibility. Medpor is reported
[21]
rate substantially higher than that of autologous tissue, the to be able to achieve similar outcomes and lower infection
necessity for immunosuppressive pharmacotherapy, and rates than autologous bone. [8]
potential risk of viral transmission. [22-24]
Non-porous, non-absorbable materials include silicone,
[30]
Xenograft mainly includes collagen membrane, porcine polytetrafluoroethylene (teflon), nylon foil. Silicone is cheap,
sclera, porcine skin gelatin/gelfilm, bovine bone or sclera. It flexible and easy to handle. However, it has unacceptable high
is only rarely used for the repair of orbital fractures because rates of extrusion, cyst formation, and infections. Teflon is
of the association with disease transmission, immunological biologically and chemically inert, non-antigenic with minimal
transplant rejection, and unpredictable and high resorption foreign body reaction, sterilizable, and easily moldable.
[31]
rates in spite of a reduction in operative time and lack of However, with the proven reliability of porous materials,
donor site morbidity. [25] nonporous materials such as polytetrafluoroethylene are
not used as frequently. Nylon has been used since 1965 by
METALS Browning and Walker with a lot of complications. Recent
[32]
studies utilize fixation of the implant to the inferior orbital
Studies have shown that titanium and cobalt alloys used rim in blow-out fractures, demonstrating a complication
to be active in the stage of orbital skeleton repair. rate as low as 1.7%. [33]
[26]
Cobalt alloys seem not that gratifying because of its poor
performance in orbital surgery and have gradually been As for absorbale implants like PLA/PGA, PDS, they have been
used in the field of surgery for years with more predictable
absorbtion rates as well as higher level of control than
biomaterials. They provide temporary support leaving
fibrotic tissues. Generally, they are not encouraged to be used
in orbital reconstruction considering their unsatisfactory
effect and high incidence of complications. [13]

BIOLOGICAL CERAMICS

Figure 2: (A) Titanium to be used in orbital reconstruction, especially for
large defect; (B) titanium mesh placed in the orbit. Adpated from Ellis and Hydroxyapatite (HA), which is chemically and
Messo [27] crystallographically similar to bone mineral, has been
88 Plast Aesthet Res || Vol 3 || Mar 23, 2016